Portable post driving apparatus

Abstract

A portable power driven post driver. The post driver has an inner hollow cylinder open at its upper end and adapted to receive a post through a locking mechanism located at its lower end. The inner cylinder is located within an outer hollow cylinder in sliding engagement therewith, the outer cylinder having a closed upper end in contact with the upper end of a post held in said inner cylinder. Two fluid powered cylinders and associated pistons are attached to the outer surface of the outer cylinder, the longitudinal axes of the two fluid powered cylinders being in alignment. A common piston rod extends between the two pistons and is attached by a fastening member to the inner cylinder, the fastening member extending through a slot in the outer cylinder. A valve receives compressed fluid, such as compressed air, and cyclically and alternately directs the compressed fluid to the two fluid powered cylinders to alternately raise the outer cylinder above the inner cylinder and to drive the upper cylinder downwardly into post driving contact with the upper end of a post held by the inner cylinder.

The invention claimed is: 
     
       1. A portable power driven post driver comprising: an inner hollow cylinder open at an upper end for receiving and holding a post;   an outer hollow cylinder having a closed upper end;   said inner cylinder being located inside said outer cylinder in sliding engagement therewith;   a first fluid powered cylinder and piston attached to an upper outer surface of said outer cylinder;   a second fluid powered cylinder and piston attached to a lower outer surface of said outer cylinder, longitudinal axes of said first and second fluid powered cylinders being in alignment;   a piston rod connecting said first and second pistons, said piston rod being attached to said inner cylinder by fastening means extending through a slot in a wall of said outer cylinder;   a valve for receiving compressed fluid and cyclically directing fluid to said first fluid powered cylinder through a first conduit to raise said outer cylinder above said inner cylinder from a first position and then directing fluid to said second fluid powered cylinder through a second conduit to thereby drive said outer cylinder down to said first position.   
     
     
       2. The post driver of claim 1 wherein said valve is a four way spool valve. 
     
     
       3. The post driver of claim 1 wherein said valve has a pivotable control lever having inner and outer ends, said control lever causing said valve to direct fluid under pressure to said upper power cylinder when the inner end of said control lever is in a down position and to said lower power cylinder when the inner end of said control lever is in an up position, said post driver including a deactuation pin attached to said piston rod, the outer end of said control lever being in alignment with said deactuation pin whereby extension of said outer cylinder causes said deactuation pin to contact and push down on the outer end of said control lever to thereby raise the inner end thereof, said control lever being configured such that the inner end thereof drops to the down position upon application of an inertial force thereto, said inertial force being that generated by post driving contact of the closed upper end of said outer cylinder with the upper end of said post. 
     
     
       4. The post driver of claim 1 wherein a clamp sleeve is located at a lower end of said inner cylinder for securely fastening a post placed in said inner cylinder. 
     
     
       5. The post driver of claim 4 wherein said clamp sleeve has an opening therein for receiving said post, said opening have a cross sectional configuration corresponding to a cross sectional configuration of said post. 
     
     
       6. The post driver of claim 5 wherein said cross sectional configuration of said opening in said clamp sleeve is T-shaped. 
     
     
       7. The post driver of claim 1 including a handle attached to the outer surface of said outer cylinder. 
     
     
       8. The post driver of claim 1 wherein said upper and lower power cylinders are configured for pneumatic operation. 
     
     
       9. The post driver of claim 8 wherein said upper and lower power cylinders are configured to operate at an air pressure of less than about 100 psi. 
     
     
       10. The post driver of claim 9 wherein said upper and lower power cylinders are configured to operate at an air pressure of between about 70 and about 90 psi.